Red, green, and blue LED (Light Emitting Diode) have been developed which can produce high brightness and a white color based on development of metal organic chemical vapor deposition and molecular beam epitaxy of GaN.
Since the LED is environment friendly as the LED does not contain substances harmful to environment, such as mercury, used in related art lighting devices, such as incandescent lamps and fluorescent lamps, and is advantageous in that the LED has a long lifetime, and low power consumption, the LED is replacing the present light sources. Core competitiveness of the LED lies on embodiment of high brightness owing to high efficiency•high power chips and packaging technologies.
For embodiment of the high brightness, it is important to enhance light extraction efficiency. In order to enhance the light extraction efficiency, different methods are under study by using a flip-chip structure, surface texturing, patterned sapphire substrate PPS, a photonic crystal technology, an anti-reflection layer structure, and so on.